One of the most widely used and important tools employed by dentists and dental hygienists is the hand-held drill which is typically a hand-held piece specifically designed and having a shape which provides for proper orientation within the mouth of the patient without requiring any awkward or unusual contortions on the part of the operator in order to appropriately position the operating end of the hand-held drill piece for the purpose of drilling, cutting, polishing, buffing, hammering, tamping and the like. The patient's mouth is a confined area requiring the skilled operator to exercise a high degree of care in the performance of dental procedures. It is quite imperative that the immediate region of concern be adequately lighted so that the operator is confident that he is performing the proper function in the proper location. This capability has been very adequately provided for in the form of an elongated fiber optic bundle having its proximal end positioned immediately adjacent a source of illumination and having its distal end mounted within the body of the drill handpiece and positioned adjacent the output shaft of the drill to flood the area of concern with light of an adequate level to permit the operator to perform the desired procedures in an assured manner.
The articulated design of the handpiece, tool and supply tray and even the dental chair enable these members to be easily manipulated and movable with the objectives of both patient comfort and operator efficiency in mind. As a result, it is most advantageous and in many cases even necessary to place the lamp source and power unit provided therefore in some location where it does not interfere with the articulated equipment employed by the operator during the performance of normal dental procedures. Since the drill handpiece is normally utilized in an intermittent fashion, it is most efficient and economical to be able to turn the lamp source on and off in a simple and straightforward fashion. This basic capability is adequately provided for as taught by U.S. Pat. No. 3,758,951 issued Sept. 18, 1973, and assigned to the assignee of the present invention, wherein a small, compact, lightweight unit identified therein as a remote control unit (RCU) is adapted to be positioned in the immediate vicinity of the work area, and which is provided with an on/off switch within easy reach of the operator to enable quick and simple turn off or turn on of the lamp source, and wherein the small size of the remote control unit enables the unit to be positioned within easy reach of the operator (typically beneath the articulated tray) without in any way interfering with other apparatus in the vicinity or with the access of the operator to such apparatus.
The conventional approach for such on/off control means is to provide an electrical circuit including switch means mounted within the remote control unit and coupled across a pair of conductive leads extending between the remote control unit and the illuminating lamp supply source. The switch may be selectively turned on and off in order to respectively energize and deenergize the light source to convey light to the area of concern by way of the fiber optics bundles.
Since water is continuously utilized during many of the dental procedures such as, for example, to cool the drill bit and tooth during drilling as well as to periodically rinse a drilled tooth to facilitate examination to determine the progress of any procedure, it is not only important but frequently required by both local and Federal regulations that the level of electrical energy of any electronic components present in the immediate working area be no greater than 21 volts at virtually zero current to protect both operator and patient from electrical shock or injury. With the apparatus of the above-mentioned issued patent, this is accomplished by providing a step-down transformer within the housing of the supply source to reduce the voltage output derived from a conventional wall receptacle typically rated at 115 volts AC, down to the above-mentioned voltage/current level. Although this technique reduces the output power delivered to the remote control unit, the danger of minor shock is still present. In addition thereto, the weight of the step-down transformer required for the above application, together with its size makes the supply source unit unduly large and heavy, serving to increase the cost of the equipment and imposing physical restrictions on both the ease of mounting and the locations in, on or upon which the unit may be mounted.